The invention relates to the preparation of concentrated anion-deficient salt solutions.
Anion-deficient salt solutions are for instance suitable for the preparation of solid oxide and carbide particles.
For the preparation of spherical particles of ceramic nuclear fuel an anion-deficient solution of uranylnitrate can successfully be used as a starting material.
In the prior art these solutions have been prepared according to the following methods:
(1) By dissolving UO.sub.3 in concentrated uranyl nitrate solutions,
(2) By the extraction of nitric acid from stoichiometric, possibly slightly acid uranyl nitrate solutions.
These methods show, however, the following drawbacks.
For the purpose of the first method it is necessary to have at one's disposal a UO.sub.3 of such a texture that this substance easily dissolves in the uranyl nitrate solution.
As to the second method it is observed that extraction, whereby nitric acid is withdrawn from a stoichiometric or weakly acid uranyl nitrate solution, can only be applied to dilute uranyl nitrate solutions. Moreover, a special installation is needed for this. After removal of the nitric acid the solution obtained has to be brought to the required degree of concentration, e.g. by evaporation.
The invention aims at giving improved methods for the preparation of an anion-deficient uranyl nitrate solution. Besides it appeared that anion-deficient actinide salt-solutions could be prepared according to several more methods than was formerly possible.